Q: What is stage 3?
A: The stage 3 chip includes all the goodies from stage 1 and 2 plus special compensation for Fuel Injector size, i.e. 660s or higher, Dead time Compensation, MAS Adjustments, Idle speed change, and Enhanced Closed Loop Operation.
Q: What is Compensation for Fuel Injector Size? I already have an AFC or MAFT, so do I really need the Stage 3?
A: If you already have an AFC, AFR, VPC, MAF Translator or some other method of fuel control, you may wonder why you would need to correct for it in the ECU. Well, the big problem is that all those air/fuel controllers work on the same principal: they lie to the ECU about the airflow, to get the ECU to reduce the injector pulse width. And, yes, it does work. However, the ECU also uses the amount of airflow to decide many other things, like what timing advance or A/F ratio to use. So, the larger the injector you have, the more the piggyback computer LIES to the ECU, and the further off the factory maps you are running. This may be great for racing at the track with C16 fuel, where leaner A/F's and more timing advance can help, but on pump gas this means LOTS of knock. By correcting for the injectors in the ECU, using the Mitsubishi "Global Fuel" location, you can allow the ECU to see the full airflow amount, and still run on the proper maps!
Q: What is MAS Adjustment?
A: The Mass Air Flow sensor airflow chart can be adjusted according to the different airflow sensors available on the market such as 2g MAS, 3G MAS, EVO MAS, and GM MAF with Translator.
Q: What is Idle Speed Changes? What idle speed should I pick with XXXX cams?
A: This option is designed for guys with really BIG cams, that have problems with insufficient vacuum at idle. Depending upon other variables, like which grind/brand cams they are, whether you have a lightened flywheel or not, whether you run a VPC, and how much vacuum you pull at idle, you may need more or less idle compensation. Unless you run a VPC, 859 to 900 is the highest idle rpm most people need. I run HKS 264 cams in #1886/2000, and it idles fine at 800 rpm, now that the rings are broke in. If I increase your idle speed setting, the ECU will use the ISC to try to maintain that new rpm. You still need to reset the BISS to the new rpm, using the idle setting procedure in the VFAQ. Related info: www.vfaq.com by Tom Stangl
Q: Will the extended closed-loop operation effect me if I go to the track?
A: No. Normally, the ECU switches to open-loop mode when the rpm or TPS exceed a certain value. My extended closed-loop feature simply moves that crossover point 500 rpm higher. However, if you exceed 40% TPS the ECU still goes open-loop, so nothing really changes for WOT operation at the track.
Q: What is Enhanced Closed Loop Operation?
A: The ECU will only stay in closed-loop mode until 4000 rpm at 35% throttle. I have extended the map to a little over 40% throttle at 5000 rpm. This will allow you to run at higher highway speeds (80+ mph) while staying in closed-loop mode for better fuel economy! Note: If you don't cruise at 80+ mph, you really don't need this feature.
